From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0A46CC433EF for ; Tue, 21 Jun 2022 05:17:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345119AbiFUFRQ (ORCPT ); Tue, 21 Jun 2022 01:17:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40490 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343981AbiFUFRO (ORCPT ); Tue, 21 Jun 2022 01:17:14 -0400 Received: from alexa-out.qualcomm.com (alexa-out.qualcomm.com [129.46.98.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 464C220F5D; Mon, 20 Jun 2022 22:17:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1655788634; x=1687324634; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=DjJMR92QYWj6k70zoT1/F5wl329J/DDEyFJrt7RMfaI=; b=Wpq/04DbTJ/uvQ30/mnE9QsVTfY8wKzisGXJZugyxXV2Gn0DnAA8DLxQ Cj9rH5S9HirU7PG081yjV6OkNghqqZL67IhUcuG3KLnKQAdeEIB4f9cXP o67w7YSMdBfc9NOzuPkyZ8KJa2wESEMtgk8RZups+YuVfiD8y9VfC0YkY U=; Received: from ironmsg-sd-alpha.qualcomm.com ([10.53.140.30]) by alexa-out.qualcomm.com with ESMTP; 20 Jun 2022 22:17:14 -0700 X-QCInternal: smtphost Received: from nasanex01b.na.qualcomm.com ([10.46.141.250]) by ironmsg-SD-alpha.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Jun 2022 22:10:59 -0700 Received: from [10.50.44.13] (10.80.80.8) by nasanex01b.na.qualcomm.com (10.46.141.250) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Mon, 20 Jun 2022 22:10:57 -0700 Message-ID: Date: Tue, 21 Jun 2022 10:40:54 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH rcu 2/3] doc: Document the rcutree.rcu_divisor kernel boot parameter Content-Language: en-US To: "Paul E. McKenney" , CC: , , , Eric Dumazet References: <20220620221733.GA3839136@paulmck-ThinkPad-P17-Gen-1> <20220620221757.3839212-2-paulmck@kernel.org> From: Neeraj Upadhyay In-Reply-To: <20220620221757.3839212-2-paulmck@kernel.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nasanex01b.na.qualcomm.com (10.46.141.250) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/21/2022 3:47 AM, Paul E. McKenney wrote: > This commit adds kernel-parameters.txt documentation for the > rcutree.rcu_divisor kernel boot parameter, which controls the softirq > callback-invocation batch limit. > > Cc: Eric Dumazet > Signed-off-by: Paul E. McKenney > --- Reviewed-by: Neeraj Upadhyay > Documentation/admin-guide/kernel-parameters.txt | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index 2522b11e593f2..bdf431bdbfdc4 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -4666,6 +4666,21 @@ > When RCU_NOCB_CPU is set, also adjust the > priority of NOCB callback kthreads. > > + rcutree.rcu_divisor= [KNL] > + Set the shift-right count to use to compute > + the callback-invocation batch limit bl from > + the number of callbacks queued on this CPU. > + The result will be bounded below by the value of > + the rcutree.blimit kernel parameter. Every bl > + callbacks, the softirq handler will exit in > + order to allow the CPU to do other work. > + > + Please note that this callback-invocation batch > + limit applies only to non-offloaded callback > + invocation. Offloaded callbacks are instead > + invoked in the context of an rcuoc kthread, which > + scheduler will preempt as it does any other task. > + > rcutree.rcu_nocb_gp_stride= [KNL] > Set the number of NOCB callback kthreads in > each group, which defaults to the square root